System and method for supplying lube oil to a gas turbine

ABSTRACT

A system for supplying lube oil to a gas turbine includes an auxiliary lube oil skid and an auxiliary lube oil pump. A first fluid connection to supply piping of a main lube oil system is downstream from the auxiliary lube oil pump. A second fluid connection to return piping of the main lube oil system is upstream from the auxiliary lube oil pump. A method for supplying lube oil to a gas turbine includes connecting an auxiliary lube oil pump to supply piping of a main lube oil system, connecting the auxiliary lube oil pump to return piping of the main lube oil system, and operating the auxiliary lube oil pump to supply lube oil to the supply piping.

FIELD OF THE INVENTION

The present invention generally involves a system and method for supplying lube oil to a gas turbine. In particular embodiments, the system and method may reduce the energy consumption of the gas turbine while shutdown.

BACKGROUND OF THE INVENTION

Gas turbines require a reliable supply of lube oil during operations for both lubrication, control systems, and heat removal. A typical main lube oil system may include, for example, redundant AC main lube oil pumps, one or more DC main lube oil pumps, a heat exchanger, and one or more circulating water pumps. The AC main lube oil pumps and circulating water pumps may be 100-125 horsepower each and designed for continuous operation, while the DC main lube oil pump(s) may be designed for backup or emergency operation. During operations, the main lube oil system supplies lube oil to lubricate components in the gas turbine, provide hydraulic fluid for control systems, and remove heat from the gas turbine. The heated lube oil then flows through the heat exchanger where water supplied by the circulating water pumps removes heat from the lube oil.

Some gas turbines are designated as “peaker” or “peaking” units and are therefore operated as needed, e.g., less than 2,000 hours per year, to supplement power generation during peak demand intervals. When the peaking units are shut down for extended periods, a turning gear or ratchet may be used to periodically jack the rotor to prevent the buildup of corrosive deposits and/or bowing. Although operation of the turning gear or ratchet requires a continuous supply of lube oil to the turning gear, bearing lift oil system, gas turbine bearing, and generator bearings, the required flow rate of the lube oil is substantially less than when the gas turbine is operating. In addition, the temperature of the components receiving lube oil flow is substantially reduced when the gas turbine is shut down, producing a corresponding reduction in the heat removal requirements of the main lube oil system. As a result, operation of the main lube oil system to supply lube oil and cooling to the gas turbine results in unnecessary power consumption and equipment wear when the gas turbine is shut down and the turning gear is being used to rotate the rotor. Therefore, an improved system and method for supplying lube oil to the gas turbine when the gas turbine is shut down that reduces the energy consumption of the lube oil system would be useful.

BRIEF DESCRIPTION OF THE INVENTION

Aspects and advantages of the invention are set forth below in the following description, or may be obvious from the description, or may be learned through practice of the invention.

One embodiment of the present invention is a system for supplying lube oil to a gas turbine. The system includes an auxiliary lube oil skid and an auxiliary lube oil pump on the auxiliary lube oil skid. A first fluid connection to supply piping of a main lube oil system is downstream from the auxiliary lube oil pump so that lube oil flows through the first fluid connection into the supply piping of the main lube oil system. A second fluid connection to return piping of the main lube oil system is upstream from the auxiliary lube oil pump so that lube oil flows from the return piping of the main lube oil system through the second fluid connection.

Another embodiment of the present invention is a system for supplying lube oil to a gas turbine that includes a main lube oil pump. Supply piping downstream from the main lube oil pump provides fluid communication from the main lube oil pump to a component of the gas turbine. Return piping downstream from the component of the gas turbine provides fluid communication from the component of the gas turbine to the main lube oil pump. An auxiliary lube oil skid includes an auxiliary lube oil pump, a first fluid connection downstream from the auxiliary lube oil pump to the supply piping, and a second fluid connection upstream from the auxiliary lube oil pump to the return piping.

In yet another embodiment of the present invention, a method for supplying lube oil to a gas turbine includes connecting an auxiliary lube oil pump to supply piping of a main lube oil system, wherein the supply piping provides fluid communication from a main lube oil pump to a component of the gas turbine. The method further includes connecting the auxiliary lube oil pump to return piping of the main lube oil system, wherein the return piping provides fluid communication from the component of the gas turbine to the main lube oil pump, and operating the auxiliary lube oil pump to supply lube oil to the supply piping.

Those of ordinary skill in the art will better appreciate the features and aspects of such embodiments, and others, upon review of the specification.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present invention, including the best mode thereof to one skilled in the art, is set forth more particularly in the remainder of the specification, including reference to the accompanying figures, in which:

FIG. 1 is a functional block diagram of an exemplary gas turbine according to one embodiment of the present invention;

FIG. 2 is a functional block diagram of a main lube oil system according to one embodiment of the present invention; and

FIG. 3 is a functional block diagram of an auxiliary lube oil system according to one embodiment of the present invention.

DETAILED DESCRIPTION OF THE INVENTION

Reference will now be made in detail to present embodiments of the invention, one or more examples of which are illustrated in the accompanying drawings. The detailed description uses numerical and letter designations to refer to features in the drawings. Like or similar designations in the drawings and description have been used to refer to like or similar parts of the invention. As used herein, the terms “first,” “second,” and “third” may be used interchangeably to distinguish one component from another and are not intended to signify location or importance of the individual components. In addition, the terms “upstream” and “downstream” refer to the relative location of components in a fluid pathway. For example, component A is upstream from component B if a fluid flows from component A to component B. Conversely, component B is downstream from component A if component B receives a fluid flow from component A.

Each example is provided by way of explanation of the invention, not limitation of the invention. In fact, it will be apparent to those skilled in the art that modifications and variations can be made in the present invention without departing from the scope or spirit thereof. For instance, features illustrated or described as part of one embodiment may be used on another embodiment to yield a still further embodiment. Thus, it is intended that the present invention covers such modifications and variations as come within the scope of the appended claims and their equivalents.

Various embodiments of the present invention include a system and method for supplying lube oil to a gas turbine. The system and method generally include an auxiliary lube oil system that may be connected in parallel to a main lube oil system to supply lube oil and/or cooling to components of the gas turbine when the gas turbine is shut down. In particular embodiments, the auxiliary lube oil system may be mounted on a skid to enhance portability of the system. Alternately, or in addition, the auxiliary lube oil system may include a control system that permits operation of the auxiliary lube oil system only after one or more predetermined limits or conditions are met to ensure that the auxiliary lube oil system can satisfy the flow and cooling requirements of the gas turbine. Although various embodiments of the present invention will be described and illustrated in the context of a gas turbine, one of ordinary skill in the art will readily appreciate from the teachings herein that embodiments of the present invention may be used with other turbo-machines, and the present invention is not limited to gas turbines unless specifically recited in the claims.

FIG. 1 provides a functional block diagram of an exemplary gas turbine 10 used to generate electrical power according to one embodiment of the present invention. As shown, the gas turbine 10 generally includes an inlet section 12, a compressor section 14 downstream from the inlet section 12, a combustion section 16 downstream from the compressor section 14, a turbine section 18 downstream from the combustion section 16, and an exhaust section 20 downstream from the turbine section 18. The inlet section 12 purifies and otherwise conditions a working fluid (e.g., air) that flows into the compressor section 14. The compressor section 14 produces a compressed working fluid that flows to the combustion section 16 where it mixes with fuel before combusting to produce combustion gases having a high temperature and pressure. The combustion gases flow through the turbine section 18 to produce work, and the exhaust section 20 purifies and otherwise conditions the combustion gases prior to further use and/or discharge to the environment.

Various components of the gas turbine 10 receive lube oil for lubrication, hydraulic control, heat removal, and/or other functions. As shown in FIG. 1, for example, a rotor 22 may connect the compressor section 14 to the turbine section 18, and lube oil 24 may be provided to lubricate bearings 26 that support the rotor 22. In addition, operation of the gas turbine 10 may generate substantial heat to the rotor 22 and bearings 26, and the lube oil 24 supplied to lubricate the bearings 26 may also remove some of the heat generated by operation of the gas turbine 10.

FIG. 2 provides a functional block diagram of a main lube oil system 30 that may be used to supply lube oil 24 to the gas turbine 10 according to one embodiment of the present invention. As shown in FIG. 2, the main lube oil system 30 generally includes one or more lube oil pumps 32 and supply piping 34 and return piping 36 that provide fluid communication between the lube oil pumps 32 and a component 40 of the gas turbine 10 that requires lubrication, hydraulic fluid, and/or cooling. The main lube oil pumps 32 may include AC and/or DC powered motors that provide redundant power to the pumps 32 to pump the lube oil 24 through the supply and return piping 34, 36. For example, in particular embodiments, the main lube oil pumps 32 may generate 100-150 horsepower of force, or more depending on the gas turbine size, to produce sufficient pressure and flow rate in the main lube oil system 30.

The supply piping 34 is downstream from the main lube oil pumps 32 and provides fluid communication from the main lube oil pumps 32 to the component 40 needing lubrication, hydraulic fluid, and/or heat removal. Similarly, the return piping 36 is downstream from the component 40 and provides fluid communication from the component 40 back to the main lube oil pumps 32. In particular embodiments, as shown in FIG. 2, the main lube oil system 30 may further include a main heat exchanger 42 and/or a sump tank 44. The main heat exchanger 42 may include a tube and fin or tube and tube arrangement that allows for the efficient removal of heat from the lube oil 24 flowing through the main heat exchanger 42. For example, the lube oil 24 may flow through tubes in the main heat exchanger 42, and a circulating pump 46 may supply a cooling media, such as water or air, to flow across or through the main heat exchanger 42 to remove heat from the lube oil 24 as is known in the art. In this manner, the lube oil 24 may cool the components 40 by transferring heat from the components 40 to the main heat exchanger 42.

The sump tank 44 may also be in fluid communication with the return piping 36 to provide a surge volume for the lube oil 24 in the main lube oil system 30. In this manner, the sump tank 44 may ensure that sufficient net positive suction head is readily available to the main lube oil pumps 32. In addition, the sump tank 44 may allow for particulate contaminants in the lube oil 24 to settle out to purify the lube oil and reduce unnecessarily fouling components 40 having tight clearances.

The main lube oil system 30 is operated continuously during normal operations of the gas turbine 10 to supply lubrication, hydraulic fluid, and/or cooling to the gas turbine 10. As shown in FIG. 2, one or more temperature sensors 48 and/or pressure or flow sensors 50 may be located throughout the main lube oil system 30, as desired, to monitor the lube oil 24 temperature, pressure, and/or flow to ensure sufficient lubrication, hydraulic fluid, and/or cooling is available to each component 40. The main lube oil system 30 is also often operated continuously when the gas turbine 10 is shut down, even though the need for lubrication, hydraulic fluid, and/or cooling is substantially reduced or eliminated. The continued operation of the main lube oil pumps 32 and circulating pump 46, if present, when the gas turbine 10 is shut down unnecessarily increases the power consumption and wear and tear associated with the main lube oil system 30 that could otherwise be reduced or eliminated if smaller capacity lube oil pumps were readily available. As a result, the main lube oil system 30 may further include one or more quick disconnects 52 at various locations to allow an auxiliary lube oil system to connect to the main lube oil system 30 as desired to supplement one or more functions of the main lube oil system 30.

FIG. 3 provides a functional block diagram of an auxiliary lube oil system 60 according to one embodiment of the present invention. As shown in FIG. 3, the auxiliary lube oil system 60 may include complementary quick disconnects 62 and may be temporarily or permanently located on a skid 64 to facilitate ease of connection and portability to the main lube oil system 30. In its simplest form, the auxiliary lube oil system 60 includes an auxiliary lube oil pump 66 that may be powered by an AC and/or DC motor. In the particular embodiment shown in FIG. 3, the auxiliary lube oil pump 66 includes a predetermined size AC/DC motor 68 provided with a reliable source of power to supply the components 40 with lube oil 24 at sufficient pressures and flow rates while the gas turbine 10 is shut down. In this manner, the quick disconnects 52, 62 between the main and auxiliary lube oil systems 30, 60 allow the auxiliary lube oil pump 66 to be connected in parallel to the main lube oil pumps 32. Specifically, the quick disconnects 52, 62 may provide a first fluid connection from the output of the auxiliary lube oil pump 66 to the supply piping 34 of the main lube oil system 30 so that lube oil 24 flows through the first fluid connection into the supply piping 34 of the main lube oil system 30. Similarly, the quick disconnects 52, 62 may provide a second fluid connection to the return piping 36 of the main lube oil system 30 so that lube oil 24 flows from the return piping 36 of the main lube oil system 30 through the second fluid connection. As a result, the smaller auxiliary lube oil pump 66 may be operated instead of the larger main lube oil pumps 32 when the gas turbine 10 is shut down and no longer requires lube oil 24 at the pressure and/or flow rates provided by the main lube oil system 30, reducing the power consumption when the gas turbine 10 is shut down.

In particular embodiments, the auxiliary lube oil system 60 may further include an auxiliary heat exchanger 70 on the auxiliary lube oil skid 64, and the quick disconnects 52, 62 between the main and auxiliary lube oil systems 30, 60 may provide fluid communication between the auxiliary heat exchanger 70 and the auxiliary lube oil pump 66. The auxiliary heat exchanger 70 may include a tube and fin or tube and tube arrangement that allows for the efficient removal of heat from the lube oil 24 flowing through the auxiliary heat exchanger 70, as previously described with respect to the main heat exchanger 42. For example, the lube oil 24 may flow through tubes in the auxiliary heat exchanger 70, and an auxiliary cooling pump 72 may supply a cooling media, such as water or air, to flow across or through the auxiliary heat exchanger 70 to remove heat from the lube oil 24 as is known in the art. In this manner, the auxiliary lube oil system 60 may supply a reduced heat removal capability compared to the main lube oil system 30, with a corresponding reduction in the power consumption when the gas turbine 10 is shut down.

The auxiliary lube oil system 60 may include operating conditions and/or mechanical interlocks to ensure that the auxiliary lube oil system 60 is not inadvertently operated in conjunction with or in place of the main lube oil system 30. Alternately, or in addition, as further shown in FIGS. 2 and 3, particular embodiments may further include a control circuit 80 operably connected to one or more control valves and/or the auxiliary lube oil pump 66 to prevent inadvertent operation of the auxiliary lube oil system 60 unless a predetermined condition exists or is satisfied. The control circuit 80 may include, for example, a controller 82 that receives one or more signals reflective of the operating status of the gas turbine 10. The technical effect of the controller 82 is to compare the signal(s) reflective of the operating status of the gas turbine 10 to the predetermined condition and generate a control signal for operating the control valves and/or the auxiliary lube oil pump 66 once the predetermined condition exists or is satisfied. As used herein, the controller 82 may comprise any combination of microprocessors, circuitry, or other programmed logic circuit and is not limited to any particular hardware architecture or configuration. Embodiments of the systems and methods set forth herein may be implemented by one or more general-purpose or customized controllers 82 adapted in any suitable manner to provide the desired functionality. The controller 82 may be adapted to provide additional functionality, either complementary or unrelated to the present subject matter. For instance, one or more controllers 82 may be adapted to provide the described functionality by accessing software instructions rendered in a computer-readable form. When software is used, any suitable programming, scripting, or other type of language or combinations of languages may be used to implement the teachings contained herein. However, software need not be used exclusively, or at all. For example, as will be understood by those of ordinary skill in the art without required additional detailed discussion, some embodiments of the systems and methods set forth and disclosed herein may also be implemented by hard-wired logic or other circuitry, including, but not limited to application-specific circuits. Of course, various combinations of computer-executed software and hard-wired logic or other circuitry may be suitable, as well.

In the particular embodiment shown in FIGS. 2 and 3, for example, the auxiliary lube oil system 60 may include one or more flow control valves 84 on the auxiliary lube oil skid 64 between the auxiliary lube oil pump 66 and the first and/or second fluid connections. The control valves 84 may include any valve known in the art for stopping and/or throttling fluid flow. The controller 82 may receive one or more temperature and/or pressure signals 86 from the temperature and/or pressure sensors 48, 50 in the main lube oil system 30, and the controller 82 may compare the signals 86 to predetermined temperature and/or pressure limits which must be met before the controller 82 will enable operation of the auxiliary lube oil system 60. For example, once the predetermined conditions are satisfied, the controller 82 may send a control signal 88 to the control valves 84 and/or the auxiliary lube oil pump 66 to enable operation of the auxiliary lube oil system 60. In still further embodiments, the controller 82 may receive additional signals indicative of the operating condition of the gas turbine 10. For example, the controller 82 may receive signals reflective of the temperature of the components 40, the time since the gas turbine 10 was shut down, ambient temperature, the level of the sump tank 44, and so forth. Based on these signals, the controller 82 may then determine based on existing protocol whether the auxiliary lube oil system 60 can supply sufficient lubrication, hydraulic fluid, and/or cooling to the components 40 of the gas turbine 10.

The embodiments shown in FIGS. 1-3 may also provide a method for supplying lube oil 24 after the gas turbine 10 has been shut down. For example, the embodiments shown in FIGS. 1-3 may supply lube oil 24 to the gas turbine 10 to support periodic turning gear operations that reduce moisture accumulation and/or bowing of the rotor 22. The method may include, for example, connecting the first and second fluid connections using the quick disconnects 52, 62 to connect the auxiliary lube oil pump 66 to the supply piping 34 and the return piping 36 of the main lube oil system 30 and operating the auxiliary lube oil pump 66 to supply lube oil 24 to the supply piping 34. In particular embodiments, the method may further include connecting the auxiliary heat exchanger 70 to the supply and return piping 34, 36 to remove heat from the lube oil 24 with the auxiliary heat exchanger 70 in fluid communication with the auxiliary lube oil pump 66 and/or operating the auxiliary cooling pump 72 to remove heat from the auxiliary heat exchanger 70. In still further embodiments, the method may include verifying that a predetermined condition exists prior to connecting the auxiliary lube oil pump 66 to the supply and/or return piping 34, 36 of the main lube oil system 30. Alternately or in addition, the method may include verifying that a predetermined condition exists prior to operating the auxiliary lube oil pump 66 to supply lube oil 24 to the main lube oil system 30.

The connection of the auxiliary lube oil system 60 to the main lube oil system 30 and operation of the auxiliary lube oil pump 66 and/or auxiliary cooling water pump 72 in place of the main lube oil pumps 32 and/or circulating pump 46 provides one or more benefits over existing main lube oil systems. For example, the smaller auxiliary lube oil pump 66 and auxiliary cooling water pump 72 compared to the main lube oil pumps 32 and circulating pump 46 reduces the power consumption while providing lubrication and/or cooling to the components 40 of the gas turbine 10. In addition, the auxiliary heat exchanger 70 may not even require the additional cooling provided by the auxiliary cooling water pump 72 due to the reduced temperature of the gas turbine 10 after shut down, further reducing the power consumption. As another benefit, the use of the auxiliary lube oil system 60 in place of the main lube oil system 30 reduces wear on the main lube oil system 30 and enables repairs and maintenance on the main lube oil system 30 to be coordinated with the shutdown of the gas turbine 10. In addition, the portability of the auxiliary lube oil system 60 provided by the skid 64 enables a single auxiliary lube oil system to be relocated as necessary to meet the lube oil 24 requirements of multiple gas turbines 10 that would otherwise require multiple main lube oil systems 30 to be operating. Moreover, the portability and reliability of the AC/DC power supply used by the auxiliary lube oil system 60 allows it to serve as a redundant backup to the main lube oil system 30 in the event of power disruption or other emergency.

This written description uses examples to disclose the invention, including the best mode, and also to enable any person skilled in the art to practice the invention, including making and using any devices or systems and performing any incorporated methods. The patentable scope of the invention is defined by the claims, and may include other examples that occur to those skilled in the art. Such other examples are intended to be within the scope of the claims if they include structural elements that do not differ from the literal language of the claims, or if they include equivalent structural elements with insubstantial differences from the literal language of the claims. 

What is claimed is:
 1. A system for supplying lube oil to a gas turbine, comprising: a. an auxiliary lube oil skid; b. an auxiliary lube oil pump on said auxiliary lube oil skid; c. a first fluid connection to supply piping of a main lube oil system, wherein said first fluid connection is downstream from said auxiliary lube oil pump so that lube oil flows through said first fluid connection into the supply piping of the main lube oil system; and d. a second fluid connection to return piping of the main lube oil system, wherein said second fluid connection is upstream from said auxiliary lube oil pump so that lube oil flows from the return piping of the main lube oil system through said second fluid connection.
 2. The system as in claim 1, wherein said auxiliary lube oil pump comprises a predetermined sized AC/DC motor.
 3. The system as in claim 1, further comprising a flow control valve on said auxiliary lube oil skid between said auxiliary lube oil pump and said first fluid connection.
 4. The system as in claim 1, further comprising a flow control valve on said auxiliary lube oil skid between said second fluid connection and said auxiliary lube oil pump.
 5. The system as in claim 1, further comprising an auxiliary heat exchanger on said auxiliary lube oil skid in fluid communication with said auxiliary lube oil pump.
 6. The system as in claim 5, further comprising an auxiliary cooling pump on said auxiliary lube oil skid in fluid communication with said auxiliary heat exchanger.
 7. The system as in claim 1, further comprising a control circuit operably connected to said auxiliary lube oil pump, wherein said control circuit prevents operation of said auxiliary lube oil pump unless a predetermined condition exists.
 8. A system for supplying lube oil to a gas turbine, comprising: a. a main lube oil pump; b. supply piping downstream from said main lube oil pump, wherein said supply piping provides fluid communication from said main lube oil pump to a component of the gas turbine; c. return piping downstream from the component of the gas turbine, wherein said return piping provides fluid communication from the component of the gas turbine to said main lube oil pump; d. an auxiliary lube oil skid comprising an auxiliary lube oil pump, a first fluid connection downstream from said auxiliary lube oil pump to said supply piping, and a second fluid connection upstream from said auxiliary lube oil pump to said return piping.
 9. The system as in claim 8, wherein said auxiliary lube oil pump comprises a predetermined sized AC/DC motor.
 10. The system as in claim 8, further comprising a flow control valve on said auxiliary lube oil skid between said auxiliary lube oil pump and said first fluid connection.
 11. The system as in claim 8, further comprising a flow control valve on said auxiliary lube oil skid between said second fluid connection and said auxiliary lube oil pump.
 12. The system as in claim 8, further comprising an auxiliary heat exchanger on said auxiliary lube oil skid.
 13. The system as in claim 12, further comprising an auxiliary cooling pump on said auxiliary lube oil skid in fluid communication with said auxiliary heat exchanger.
 14. The system as in claim 8, further comprising a control circuit operably connected to said auxiliary lube oil pump, wherein said control circuit prevents operation of said auxiliary lube oil pump unless a predetermined condition exists.
 15. A method for supplying lube oil to a gas turbine, comprising: a. connecting an auxiliary lube oil pump to supply piping of a main lube oil system, wherein the supply piping provides fluid communication from a main lube oil pump to a component of the gas turbine; b. connecting said auxiliary lube oil pump to return piping of the main lube oil system, wherein the return piping provides fluid communication from the component of the gas turbine to the main lube oil pump; and c. operating said auxiliary lube oil pump to supply lube oil to the supply piping.
 16. The method as in claim 15, further comprising removing heat from the lube oil with an auxiliary heat exchanger in fluid communication with said auxiliary lube oil pump.
 17. The method as in claim 16, further comprising operating an auxiliary cooling pump to remove heat from said auxiliary heat exchanger.
 18. The method as in claim 15, further comprising verifying a predetermined condition exists prior to connecting said auxiliary lube oil pump to the supply piping of the main lube oil system.
 19. The method as in claim 15, further comprising verifying a predetermined condition exists prior to connecting said auxiliary lube oil pump to the return piping of the main lube oil system.
 20. The method as in claim 15, further comprising verifying a predetermined condition exists prior to operating said auxiliary lube oil pump to supply lube oil to the main lube oil system. 